148 THE SCOLYTID BEETLES. 



or later. Therefore there is a succession of emerging adults through- 

 out the greater part of the warm season, and it is not improbable that 

 some of them pass the second winter as matured adults. 



GENERATION. 



The broods from eggs of overwintered parent adults evidently de- 

 velop into adults, some of which emerge before hibernation begins 

 in the fall, but it is probable that most of them pass the winter as 

 matured adults. The overwintered broods of adults begin to deposit 

 eggs in March and April, and continue to do so as successive broods 

 appear until activity ceases in the fall. The eggs begin to hatch in 

 March and April, the process continuing during April and May and 

 until July or later. The principal active or feeding stage of the 

 larvae is during the period from May to July, but this stage may 

 occur in any month of the year. The more advanced broods from 

 eggs deposited in March evidently transform to pupae and adults in 

 July or August, but it appears that the principal period of transfor- 

 mation is in the fall, while the broods from eggs deposited in the sum- 

 mer do not transform until the following spring. 



It is probable that some of the adults of the earlier broods may 

 emerge in the fall, but no good evidence has been found that they 

 do so in the northern section of the distribution. There is, however, 

 such a complex overlapping of broods that it has been difficult to 

 arrive at any conclusions regarding the normal period required for 

 the development and emergence of all of the broods of a generation. 

 It is evident, however, that in the northern section there is but one 

 generation annually, and that in some cases it may require two years 

 from the appearance of the earliest broods until all of the latest broods 

 have developed and emerged and that, therefore, individuals of one 

 generation may pass over two winters, first as young larvae, and second 

 as matured adults and larvae, the latter from eggs deposited in the 

 spring by the overwintered parent adults. It may also happen, as 

 is known in some Curculionidae, that some of the adults may live 

 two years or more. 



Southern Section. 



In the region east of central North Carolina and south of western 

 North Carolina and eastern Tennessee the seasonal history differs 

 from that in the northern section, mainly in the fact that activity 

 begins earlier in the spring and continues later in the fall, that in its 

 more southern distribution it evidently continues active during the 

 entire year, and that there is one complete generation and- a par- 

 tial second, if not two generations, annually, in the most southern 

 localities. 



